1. Field of the Invention
The present invention relates to engine coolant thermostats and more particularly pertains to an engine coolant thermostat which is provided with a safety release means in the event of thermostat failure.
2. Description of the Prior Art
The use of safety devices in engine cooling systems is known in the prior art. For example, U.S. Pat. No. 4,691,669, which issued to Otteman et al. on Sep. 8, 1987, discloses an engine overheat protection system which indicates and signals the loss of coolant liquid as the result of a pressure drop at higher temperatures. This particular type of protection device relies upon a sophisticated electronic circuit to determine coolant and system pressure loss and to then activate the associated alarm.
A simpler type of safety protection device is to be found in U.S. Pat. No. 4,942,849, which issued to V. Shelton on Jul. 24, 1990 and which is directed to a fail-safe coolant thermostat system for an internal combustion engine. The disclosed thermostat utilizes a secondary cooling fluid passage which operates as a bypass valve means whenever the thermostat begins to fail or when engine temperature or coolant pressure exceeds a prescribed maximum. While being functional for its intended purpose, this type of thermostat is complex and expensive to manufacture and apparently, it has achieved no commercial success.
As such, there appears to exist a need for new and improved simple and economical safety devices which would detect and prevent engine damage due to thermostat failure. In this respect, the present invention substantially fulfills this need.